Aircraft window of synthetic resin having hard coated film and a method for producing the same

ABSTRACT

An aircraft window of synthetic resin having hard coated film and at least a double-pane construction with a hollow interspace therebetween for an aircraft cabin window or a single pane construction including a mono-layer or multi-layer pane for an aircraft cockpit, canopy, or windshield window comprises an outer synthetic resin molded body having hard coated film on the outside surface of the aircraft and an inner synthetic resin molded body facing each other to form at least a double-pane construction with a hollow interspace therebetween, or an synthetic resin molded body having hard coated film on the outside surface or both of outside and inside of the aircraft to form a single pane construction of mono-layer or multi-layer, the hard coated film comprising siloxane bonds and/or silazane bonds obtained by coating a coating composition containing perhydropolysilazane or its condensation polymer which is substantially soluble in organic solvent on the surface of the synthetic resin molded body and heat-treating the body at approximately ambient temperature to 100° C. in air or humidified air

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an aircraft window of syntheticresin having hard coated film, such as a cabin window, a cockpit window(mainly a side panel), canopy or windshield and a method for producingthe same.

[0003] 2. Description of the Related Art

[0004] Synthetic resin such as polycarbonate or polyacrylate resin hasbeen in common usage as aircraft windowpanes in light of the balance ofperformances such as transparency, strength, specific gravity anddurability. Polyacrylate resin has good moldability and easilyobtainable optical isotropy in case of producing a large size moldingbody. Polycarbonate has excellent heat resistance and impact loadcarrying capacity. These resins have been applied to the windowpane ofmany kinds of aircrafts taking advantage of each property above.

[0005] Meanwhile, aircraft windowpanes have a lot of occasions for beingsubject to abrasive damage caused by abrasion with atmospheric iceparticles or raindrops, by contact with inorganic particles such asvolcanic ash or cloud of sand or by contact with insects sticking to thesurface of the windowpanes. The surface is wiped with cleaning cloth orthe like when in maintenance and cleaning. Though these resins have noproblem with bulk strength, the surface hardness thereof is low so thatthe surface is apt to get scratched. This is the only difficulty becausethe aircraft window should functionate with good visibility. Frequentexchange of windowpanes brings about increasing maintenance cost, whichis no measure for solving the problem. Hence, recently, an aircraftwindow mounted with a resin windowpane having surface protective coatingis hoped earnestly.

[0006] However, conventional methods for applying protective coating canbe roughly categorized by (1) a method for forming a SiO₂ film bycoating a compound having Si and baking it or by (2) a method forforming a SiO₂ film by PVD such as ion-plating. The method (1) givesinsufficient hardness of the surface so that the aimed protectivitycannot be attained. The method (2) generates the peeling or cracks ofthe film owing to poor adhesion and does not give sufficientprotectivity because of difficulty in obtaining a thick film.

SUMMARY OF THE INVENTION

[0007] In view of the need to solve the prior problems, it is the objectof the present invention to provide an aircraft window of syntheticresin having hard coating with excellent hardness and durability in anaircraft cabin window having at least a double-pane construction with ahollow interspace therebetween or an aircraft cockpit, canopy, orwindshield window having a single pane construction including amonolayer or multilayer pane and to provide a method for producing thesame.

[0008] An aircraft window of synthetic resin having hard coated film andat least a double-pane construction with a hollow interspacetherebetween for an aircraft cabin window according to the presentinvention comprises an outer synthetic resin molded body having hardcoated film on the outside surface of the aircraft and an innersynthetic resin molded body facing each other to form at least adouble-pane construction with a hollow interspace therebetween, whereinthe hard coated film comprising siloxane bonds and/or silazane bondsobtained by coating a coating composition containingperhydropolysilazane or its condensation polymer which is substantiallysoluble in organic solvent on the surface of the synthetic resin moldedbody and heat-treating the body at approximately ambient temperature to100° C. in air or humidified air.

[0009] An aircraft cabin window should have a heat-insulating propertybecause of the extreme temperature difference between the inside and theoutside of the cabin, a transparency as a function of window, and astrength as a member constructing a part of the fuselage or to endurethe pressure difference between the inside and the outside of the cabin.Furthermore, considering fail-safe structure, a measure for the case thepane is damaged due to outbreak of abnormal state is necessary.Therefore, the aircraft cabin window has at least a double-paneconstruction with a hollow interspace therebetween by facing transparentsynthetic resin molded bodies with each other.

[0010] According to the present invention, one side (the outside of thecabin) of at least one of the molded bodies has the hard coated film. Atleast double-pane construction means that, in case of need, multi-panemore than double-pane construction is adopted. This improves insulatingfunction and failsafe function. In this case, the hard coat isindispensably needed on the molded body inside of the cabin whereabrasion rarely occurs.

[0011] Thus, for example, one side of a transparent molded body ofsynthetic resin such as polycarbonate or cast acrylate resin is coatedwith a solution of substantially organic-solvent-solubleperhydropolysilazane or its condensation polymer in an organic solventso that the film thickness after heat-treating comes to be from 1 μm to100 μm and the coated body is heat-treated at approximately ambienttemperature to 100° C. after drying in air. A hard film having silazanebonds and/or siloxane bonds is coated on the one side of thus obtainedtransparent molded body of synthetic resin such as polycarbonate or castacrylate resin. A window part comprises the two bodies bonded each othertogether with a spacer inserted at the outer perimeter therebetween. Thefaces having no hard coating of the two bodies are facing each other soas to be spaced apart from one another. The window part is fixed to anopening of the fuselage for a window through a gasket or a sealingmember to form a cabin window. In this case, a gasket or a sealingmember may be molded so that two bodies are spaced apart from oneanother when the two bodies are fixed through the gasket or the sealingmember and a two-pane construction is formed by fixing one body by onebody to the gasket or the sealing member.

[0012] The cast acrylate resin is a transparent synthetic resin having ahigh softening point consisting of a homopolymer or a copolymer obtainedby polymerizing a polymerizable monomer consisting mainly of methylmethacrylate. The synthetic resin is cast to a panel-formed molded bodyby heating to flow to a temperature equal to or higher than thesoftening point thereof. A windowpane can be made from the panel-formedmolded body by cutting to a form of the windowpane. A windowpane canalso be made by casting the resin to a form of the windowpane. Andbesides, a method other than these is that the monomer is poured into aboard-formed mold to cast and polymerize at the same time.

[0013] The thickness of the transparent molded body of synthetic resinis variable according to the intended strength of the fuselage or thesize of the opening of the fuselage. The spacer may be made from thesame material as the transparent molded body of synthetic resin or moreelastic material than that of the body. The gasket or the sealing memberis selected from the organic materials having appropriate elasticity,strength and durability in order to keep airtight in the cabin from theoutside where temperature difference is great and to support firmly thewindowpanes.

[0014] One of the perhydropolysilazane or its condensation polymer whichis substantially soluble in organic solvent in the coating compositionis a cyclic or linear perhydropolysilazane having a structure of theformula (1) as a repeated unit or a mixture thereof.

[0015] Further, another of the perhydropolysilazane or its condensationpolymer is an intermolecular dehydrogenation condensation polymer ofcyclic or linear perhydropolysilazanes having a structure of the formula(1) as a repeated unit or a mixture of them.

[0016] Furthermore, another of the perhydropolysilazane or itscondensation polymer is a dehydrogenation condensation polymer having aplurality of the condensation structures of (2) or (3) by condensing thecyclic or linear perhydropolysilazane having a structure of (1) withammonia or hydrazine or condensing the mixture of the cyclic and linearperhydropolysilazane having a structure of (1) with ammonia orhydrazine.

[0017] A hard coated film having siloxane bonds and/or silazane bondsaccording to the present invention has the bonds formed by coating thesilazane compound and heat-treating, the silazane bond being indicatedby the formula (4) and the siloxane bond being indicated by the formula(5).

—Si—N—  (4)

—Si—O—  (5)

[0018] According to the present invention, an aircraft window ofsynthetic resin having hard coated film and a single pane constructionincluding a mono-layer or multi-layer pane for an aircraft cockpit,canopy, or windshield window comprises an synthetic resin molded bodyhaving hard coated film on the outside surface or both of outside andinside of the aircraft to form a single pane construction of mono-layeror multi-layer, the hard coated film comprising siloxane bonds and/orsilazane bonds obtained by coating a coating composition containingperhydropolysilazane or its condensation polymer which is substantiallysoluble in organic solvent on the surface of the synthetic resin moldedbody and heat-treating the body at approximately ambient temperature to100° C. in air or humidified air.

[0019] An aircraft cockpit, canopy, or windshield window is exposed tomore severe condition than a cabin window is exposed to. Collisionchance with foreign matter is more frequent and the impact is higher.The windowpane is not only a plane surface but also a curved surface.There is another requirement of clear visibility so that irregularrefraction of penetrated light is not allowed. Thus, the windowpanecannot be a double-pane construction as a cabin window.

[0020] Accordingly, a multi-layer laminated structure is necessary inorder to attain sufficient failsafe function for single paneconstruction even if it has a curved surface. High strength resin suchas stretched polyacrylate resin is used for a main structural part.Stretching strengthens the resin because molecular arrangement turnsregular thereby. The tensile strength, compression strength and otherstrength of the resin are far higher than those of cast polyacrylateresin and the moldability and transparency remain. Material sandwichedbetween the stretched polyacrylate resins is selected from the highadherence resins which absorb the thermal expansion or shrinkage stressby the temperature difference between outside and inside of the fuselageand do not affect the other layer when the one layer gets cracked,though the material is not restricted. An electrically conductive filmheated by electric current may be sandwiched in order to preventbedewing, icing or hazing in addition to the aforementioned structuralfunction.

[0021] The windowpane having a multi-layer laminated structure has ahard coated film on the inside surface of the fuselage or hard coatedfilms on the both inside and outside surfaces because the inside surfaceis also apt to get scratched which is different from the cabin window. Asingle-layer windowpane also has both cases stated above for the samereason.

[0022] According to the present invention, a synthetic resin molded bodyof the aircraft window of synthetic resin having hard coated filmcomprises a polyacrylate resin molded body or a polycarbonate resinmolded body. The polyacrylate resin preferably comprises a castpolyacrylate resin or a stretched polyacrylate resin.

[0023] Various kinds of heretofore known perhydropolysilazanes or theircondensation polymers can be used as perhydropolysilazane or itscondensation polymer, which is substantially soluble in organic solvent,according to the present invention. For example one of the abovecompounds is a cyclic or linear perhydropolysilazane having a structureof the formula (1) as a repeated unit or a mixture thereof, which can beproduced by a method disclosed in Japanese laid open publicationP1984-207812A.

[0024] Another example of perhydropolysilazane or its condensationpolymer, which is substantially soluble in organic solvent is a compoundobtained by heating to dehydrocondense a cyclic or linearperhydropolysilazane having a structure of the formula (1) or a mixturethereof in an alkaline solvent or in a solvent containing an alkalinecompound. An example of the methods for producing the compound isdisclosed in Japanese laid open publication P1989-138108A.

[0025] Another example of perhydropolysilazane or its condensationpolymer, which is substantially soluble in organic solvent is a compoundobtained by heating to dehydrocondense a cyclic or linearperhydropolysilazane having a structure of the formula (1) or a mixturethereof through ammonia or hydrazine. An example of the methods forproducing the compound is disclosed in Japanese laid open publicationP1989-138107A.

[0026] The molecular weight of perhydropolysilazane or its condensationpolymer is not particularly restricted but preferably as high as itgives a good film and not as high as it gives appropriate workability bybeing substantially soluble in an organic solvent for coating and havingenough liquidity.

[0027] The hydrogen elements are preferably not consumed completely butremain partially unreacted, which is related to the adherence of thehardened film, whereby a strongly adhered hardened film can be formed onthe synthetic resin surface.

[0028] A solvent for coating perhydropolysilazane or its condensationpolymer on the surface of the sythetic resin is preferably a solventwhich is not reactive with SiH group. Compounds which have activehydrogen atoms such as alcohol, primary amine, secondary amine or watercontaining solvent should be avoided. Thus appropriate solvent is, forexample, aliphatic, alicyclic or aromatic hydrocarbon, halogenatedhydrocarbon, and aliphatic or alicyclic ether. Further, a mixture ofmore than two kinds of solvents can be used for adjusting solubility ofthe synthetic resin to the solvent or the evaporation rate of thesolvent. But the solvent that dissolves the synthetic resin well isinappropriate. Some kinds of aromatic hydrocarbon, ketone or ester fallinto this category. Therefore, an appropriate compound should beselected as a solvent or a non-solvent of these resins is mixed toadjust the solubility.

[0029] A coating composition containing a substantially organic solventsoluble perhydropolysilazane or its condensation polymer used in thepresent invention is a known composition which is made and sold byClariant Japan K.K. It is sold as a product name of polysilazane silicacoating L110, L710, N110, V110, D110 and L120. These are 20% xylene ordibutylether solution of perhydropolysilazane having an average numberaverage molecular weight of 700-1000 with or without an added oxidationcondensation catalyst. Each product is named according to a kind ofsolvent, molecular weight, a kind of catalyst including with or withoutcatalyst.

[0030] Coating on the surface of the molded resin body is performed byknown methods such as dipping, spraying, brush coating, spin coating,roll coating or doctor-blade coating. After coating, solvent isevaporated at low temperature and the coated resin body is heat-treatedat prescribed temperature. The heat-treating environment can be chosenfrom among humidified air, dry air, humidified inert gas and dry inertgas. The higher is the partial pressure of water or oxygen, the morerapidly the film is formed at low temperature since the rate of reactionat low temperature becomes more rapid. Further, if a coating compositioncontaining an oxydation condensation catalyst is used, it is possible toform more rapidly a coating film at lower temperature.

[0031] Further, according to the present invention, an aircraft windowof synthetic resin having hard coated film comprises a monolayer hardcoated film whose thickness is 1 μm or more and less than 10 μm aftercoating the coating composition on the surface of the molded resin bodyand heat-treating in air or humidified air.

[0032] In a conventional hard coating, a protective coating is formed bycoating a coating composition containing a compound of silicon to whichalkoxy groups are bonded, generating siloxane bonds through the steps ofhydrolysis and dealcoholization or dehydration. Unlike with a filmforming mechanism of the present invention, as bulky, high molecularalkoxy groups is broken away, causing decrease of molecular weight ofthe polymer resulting from the film forming reaction, the film has lowdensity and poor adherence. Alkoxy groups often remain depending on areaction condition, giving a film of low density and poor adherence.Therefore, a film thickness formed by this kind of reaction has itslimits of 1 μm at most. A film of more than 1 μm results in generationof cracks or deterioration of adherence by heat cycle to become far frompractical use. Such thin film coated on an aircraft window has poordurability so that a condition of cleaning work becomes severe becausethe work taking off the dirt on the outside of the fuselage needs to befrequent.

[0033] When a hard coated film having siloxane bonds and/or silazanebonds is formed by coating a coating composition containingperhydropolysilazane or its condensation polymer which is substantiallysoluble in organic solvent on the surface of the molded synthetic resinbody and heat-treating the body at approximately ambient temperature to100° C. in air or humidified air according to the present invention, thefilm forming mechanism contains conversion to siloxane bonding throughhydrolysis, oxidation, deanmonization and dehydration. The molecularweight of the resultant film polymer is essentially larger than that ofperhydropolysilazane and there is no large organic group eliminatingfrom perhydropolysilazane so as to give a very dense and adherent film.Therefore, the film thickness of 1 μm or more enables to obtain thehardness to attain the object of the present invention. The object is toobtain a coated film having high durability, enough hardness to bearabrasion and good adherence, including improvement of condition oncleaning an aircraft window.

[0034] However, durability to thermal cycle test begins to lower withthe mono-layer film when the film thickness comes to 10 μm or more,causing cracks and peeling off of the film happen.

[0035] According to the present invention, a hard coated film of anaircraft window of synthetic resin comprises substantially two layers ofan intermediate layer which coats the top surface of molded resin bodyand an outermost layer which coats the top surface of the intermediatelayer wherein after the molded resin body is coated with the coatingcomposition and heat-treated in air or in humidified air, a coated filmthickness of two layers in total is 10 μm or more and 200 μm or less.

[0036] Thus, very thick-coated film can be formed when the resin surfaceis coated with two layers according to the present invention. The coatedfilm of an aircraft window is exposed to very severe condition as iswell known and should endure a broad range temperature condition of 80°C. under direct rays of the sun in tropical zone or under friction heatof high speed flying to −50° C. under high-altitude or high-latitudeflying. If an aircraft flies at supersonic speed, the coated film of theaircraft window should endure a broader range temperature of −70 to 120°C. If the harder film is coated to ensure abrasion resistance, thermalor other stress of expansion-shrinkage cycles due to a difference ofthermal expansion between the film and substrates such as polyacrylateresin or polycarbonate resin causes cracks. Thus if the film thicknessis secured by one layer, a thickness of 10 μm is the limit because ofthe above reason.

[0037] Hence, the present inventors tried a surface treatment comprisingsteps of coating perhydropolysilazane free from catalyst, a compositionof the kind which does not harden at low temperature such as N510 orN310 and of heat-treating at 80-100° C. When coatingperhydropolysilazane free from catalyst, silazane is not perfectlyconverted to siloxane but remains partially by the heat-treatment ofsuch extent to form soft and flexible coated film of an intermediatelayer. When perhydropolysilazane containing catalyst is coated on thetop of an undercoating layer (intermediate layer) and heated toprescribed hardness and even the thickness of the coated film comes to200 μm in total, the intermediate layer absorbs stress in theundercoating layer so that crack or peeling-off does not occurs evenafter heat cycle. Such double layer coating enables a hard protectivecoated film of enough thickness.

[0038] Since silazane bonding remains in the undercoating layer, it isapprehended that a property of the film may change with time by reactingwith water in the air. It would appear that the outermost layer coatingfunctions as a barrier coating so as to block of f water or oxygen.Consequently, the double layer coating has good durability.

[0039] A practical application of the hard coated film is impossiblewithout double coating including the undercoating layer according to thepresent invention, in case of a canopy or a windshield to which thickhard coating is necessary. Double coating is not indispensable forcoating for a cabin window of a passenger carrier as thin film thicknesscan be applicable.

[0040] According to the present invention, a hard coated film thicknessof the intermediate layer in an aircraft window of synthetic resinhaving hard coated film is between 1 μm and 50 μm m. The undercoatinglayer having a thickness of less than 1 μm is not effective as anintermediate layer; the undercoating layer having a thickness of morethan 50 μl m negatively affects the strength of the coated film in totalbecause the intermediate layer is comparatively soft.

[0041] According to the present invention, in an aircraft window ofsynthetic resin having hard coated film, the coating composition for amonolayer coated film or the coating composition for the outermost layerof a double-layer coated film contains paradium catalyst. A large ovenfor high temperature is necessary in order to heat-treat a large moldedbody such as an aircraft window of synthetic resin. Thus, it isadvantageous to react at low temperature at high reaction rate by aneffective catalyst such as paradium. The coated film may also behardened in an atmosphere of a vapor of an alkaline compound having noreactive hydrogen such as trialkylamine as a catalytic measure foraccelerating the reaction.

BRIEF DESCRIPTION OF DRAWINGS

[0042] In the accompanying drawings:

[0043]FIG. 1 is a schematic drawing showing an aircraft window;

[0044]FIG. 2 is a perspective view of a cabin window and a crosssectional view along B-B′ line;

[0045]FIG. 3(A) is a perspective view of a wind shield and canopy of asmall aircraft; and

[0046]FIG. 3(B) is a cross sectional view along C-C′ line of FIG. 3(A).

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0047] The invention will now be described below in detail by way ofexample with reference to the accompanying drawings. It should beunderstood, however, that the description herein of specific embodimentssuch as to the dimensions, the kinds of material, the configurations andthe relative disposals of the elemental parts and the like is notintended to limit the invention to the particular forms disclosed butthe intention is to disclose for the sake of example unless otherwisespecifically described.

EXAMPLE 1

[0048] Polysilazane coating compositions capable of hardening at lowtemperature contain an organic amine catalyst or a paradium catalyst. Acommercially available polysilazane coating composition for polyacrylateresin, L110 is a 20% xylene solution containing a paradium catalyst andthat for polycarbonate resin, L120 is a 20% dibutylether solutioncontaining a paradium catalyst. L110 and L120 are produced and sold byClariant Japan K.K. Hard coated film was formed on a cast polyacrylateresin panel or a polycarbonate resin panel using L110 or L120 as testsolutions as follows.

[0049] A test solution was coated on an above mentioned test panel sothat a dry film thickness after treatment came to between 1 μm and 10 μmby setting an appropriate thickness of the solution film by means ofsuch as spray coating, dip coating or spin coating.

[0050] A coated test panel was dried in the air and heat-treated for anhour in the atmosphere of air having a relative humidity of 70% and atemperature of 80° C. An obtained coated film on the synthetic resinshad a thickness of approximately 5 μm and was uniform, uniform,colorless and transparent with no generation of cracks or deterioration.

[0051] Polysilazane solution was so volatile that the solvent vaporizedrapidly and it was difficult to adjust accurately the thickness ofsolution. In this case, after coating by means of such as spray coating,dip coating or spin coating and heat-treating, the coated film wasground to a film thickness of 1 μm or more and 10 μm or less.

[0052] As for a comparative example 1, SiO₂ film having a thickness ofapproximately 5 μm was coated on a polyacrylate panel and apolycarbonate panel by means of ion plating method. A uniform, colorlessand transparent film was formed. These test panels were tested asfollows.

[0053] Adherence: Gridiron was cut at a distance and depth of 1 mm onthe film of 1 cm². A piece of cellophane tape was affixed over thegridiron and then peeled off at an angle of 90 degree and at a rate of30 cm/sec. Remained boxes were counted.

[0054] Hardness: A line was drawn on the surface of a film with a pencilloaded by 100 gr weight. A pencil hardness which caused scratches wasrecorded.

[0055] Abrasive resistance: The surface of a film was abraded usingsteel wool #000 at a weight of 250 g and a rotational rate of 60 rpm.After 1000 times rotation, haze value was recorded. (Haze value is ameasure indicating scattering extent of light. The smaller the value is,the more transparent the material is.) The result is shown in table 1.TABLE 1 Test Piece Adherence Hardness Haze value Polyacrylate panelcoated 100/100 8H 3% with L110 Polycarbonate panel coated 100/100 9H2.5% with L120 Polyacrylate panel with SiO₂  60/100 8H 10% film by ionplating Polycarbonate panel with SiO₂  80/100 >9H  8% film by ionplating Polyacrylate panel uncoated — HB 15% Polycarbonate paneluncoated — H 10%

[0056] As shown in table 1, the surface hardness of the polyacrylate andpolycarbonate coated by ion plating method is the same or greater thanthat coated by polysilazane coat and bake method. As apparent shown by aresult of the tape test, haze value at abrasion test increased bygenerating cracks and peelings on account of lack of adherence.

EXAMPLE 2

[0057] With regard to evaluation of abrasion resistance, a coated filmof the present invention was compared with a conventional coated filmwith Taber Abraser described in ASTM Standard. A hard coating used forprotecting polyacrylate aircraft window in a certain country, aconventional hard coating in Japan and a hard coating according to thepresent invention were compared under the same condition. Coatedsubstrate was polyacrylate resin.

[0058] Test method was based on ASTM Standard D1044. Three testspecimens having a diameter of 102 mm and a thickness of 12.7 mm wereprepared for each test. The test specimens were conditioned and testedwith Taber Abraser under the surrounding condition described in theStandard. The abraser was attached with an abrasive wheel of CS-10F andtest was done at a rotational rate of 100 rpm with a weight of 500 gf.The light scattered by abraded tracks of the specimen was measured by aphotometer pursuant to ASTM1003. An average value of data of percentagescattered light with regard to three specimens was shown in Table 2.TABLE 2 Coating Coating used Conventional according to Acrylate incertain Coating used the present Substrate country in Japan inventionHaze value  1.15 1.15 0.75 0.73 before test Haze value 25.20 3.38 2.401.05 after test Haze value 24.05 2.23 1.65 0.32 variation

[0059] Compared with a hard coated film for an aircraft window used incertain country, the hard coated film according to the present inventionwas found to have abrasion durability seven times as much.

EXAMPLE 3

[0060] The effect of heat-treating in moistened air was tested asfollows. Test specimens coated with L110 were prepared likewise inexample 1, heat-treated under the two levels of conditions shown intable 3 and tested pursuant to the ASTM. A rotational rate of TaberAbraser was 500 rpm, 5 times as fast as that in example 2. Otherconditions are the same as in example 2. The result was shown in table3. TABLE 3 Heat-treating Ambient Humidity, condition 80° C., 5 hours 98%RH, 80° C., 5 hours Haze value before test 1.15 1.03 Haze value aftertest 5.55 2.18 Haze value variation 4.40 1.15

[0061] As shown in table 3, by heat-treating in humidified air of 98%RH, the abrasion durability (the reciprocal of the variation of hazevalue) was improved by approximately 4 times even at the sameheat-treating temperature.

EXAMPLE 4

[0062] Double layer coating according to the present invention wastested as follows.

[0063] A test specimen with a single coated film of a thickness of 50 μmwhich was prepared by coating L110 (20% xylene solution ofperhydropolysilazan having a molecular weight of 1000 containingparadium catalyst) directly on a polyacrylate test panel andheat-treating at 80° C. was compared with a test specimen with a doublecoated film which was prepared by coating N510 (20% xylene solution ofperhydropolysilazan having a molecular weight of 1200 containing nocatalyst) on a polyacrylate test panel as an undercoating andheat-treating at 80° C. to form a film of 20 μm as an intermediate layerand coating L110 on the top of the intermediate layer and heat-treatingto form a film of 110 μm as a top layer.

[0064] By a test of heating to 80° C. in the atmosphere and cooling to−20° C., no crack was generated with two kinds of specimens. Then, atest of a most severe temperature change was performed in such a mannerthat a specimen heated to 80° C. was dipped into the ice water of 0° C.As a result, though many fine cracks were generated by the rapid coolingon a specimen of acrylate coated with monolayer of L110, no crack wasgenerated on the double-coated specimen.

EXAMPLE 5

[0065]FIG. 1 is a schematic drawing showing an aircraft window. In FIG.1, 2 is a cockpit window. Inorganic glass is often used in frontwindows; polyacrylate resin is often used inside windows. 3 is a cabinwindow provided on a fuselage 1. FIG. 2 is a perspective view and across sectional view of the cabin window.

[0066] In FIG. 2, 21 is a pane outside of fuselage of cast polyacrylateresin molded body cut out as shown in the drawing and having hard coatedfilm 24 according to the present invention. A cast polyacrylate resinboard having a thickness of 15 mm was cut out to a pane with a roundshown in the drawing and the edge part was chamfered. Silazane coatingcomposition L110 of the example 1 was spray-coated to a hardenedthickness of 5 μm on one side of the pane and solvent was air-dried atan ambient temperature. After that, the coated pane was heat-treated inthe air of a temperature of 70° C. and a relative humidity of 60% fortwo hours.

[0067]22 is a inside pane of fuselage of cast polyacrylate resin moldedbody cut out as shown in the drawing.

[0068] A cabin window is constructed in such a manner that a paneoutside of fuselage having hard coated film on the one side 21 and ainside pane of fuselage having no hard coated film 22 were embedded intoa neoprene gasket 23 through a hollow interspace 25 with faces having nocoated film thereon facing each other.

EXAMPLE 6

[0069]FIG. 3(A) is a perspective view of a windshield and canopy of asmall aircraft and FIG. 3(B) is a cross sectional view along C-C′ lineof FIG. 3(A). In FIG. 3(A), 31 is a stretched polyacrylate resin windshield and 37 is a stretched polyacrylate resin canopy.

[0070]36 is a canopy frame and 35 is a windshield frame. A laminatedpane was made by sandwiching butyral resin 33 between stretchedpolyacrylate resin molded bodies 31, 31 with thickness of 20 mm.Silazane coating composition L110 of the example 1 was spray-coated to ahardened thickness of 10 μm on both sides of the pane and solvent wasair-dried at an ambient temperature. After that, the coated pane washeat-treated in the air of a temperature of 70° C. and a relativehumidity of 60% for three hours.

[0071] Thus, the windowpane having a hard coated film according to thepresent invention was fixed to the windshield frame 35 with sealant 34.

EFFECT OF THE INVENTION

[0072] The present invention can provide an aircraft window of syntheticresin having hard coating with excellent hardness and durability in anaircraft cabin window having at least a double-pane construction with ahollow interspace therebetween or an aircraft cockpit, canopy, orwindshield window having a single pane construction including amonolayer or multilayer pane and can also provide a method for producingthe same.

What is claimed is:
 1. An aircraft window of synthetic resin having hardcoated film comprising an outer synthetic resin molded body having hardcoated film on the outside surface of the aircraft and an innersynthetic resin molded body facing each other to form at least adouble-pane construction with a hollow interspace therebetween for anaircraft cabin window, the hard coated film comprising siloxane bondsand/or silazane bonds obtained by coating a coating compositioncontaining perhydropolysilazane or its condensation polymer which issubstantially soluble in organic solvent on the surface of the syntheticresin molded body and heat-treating the body at approximately ambienttemperature to 100° C. in air or humidified air.
 2. An aircraft windowof synthetic resin having hard coated film comprising an synthetic resinmolded body having hard coated film on the outside surface or both ofoutside and inside of the aircraft to form a single pane construction ofmono-layer or multi-layer for an aircraft cockpit, canopy, or windshieldwindow, the hard coated film comprising siloxane bonds and/or silazanebonds obtained by coating a coating composition containingperhydropolysilazane or its condensation polymer which is substantiallysoluble in organic solvent on the surface of the synthetic resin moldedbody and heat-treating the body at approximately ambient temperature to100° C. in air or humidified air.
 3. An aircraft window of syntheticresin having hard coated film according to claim 1 or 2 wherein the filmobtained by coating the coating composition on the surface of thesynthetic resin molded body and heat-treating in air or humidified airhas a thickness of 1 μm or more and below 100 μm.
 4. An aircraft windowof synthetic resin having hard coated film according to claim 1 or 2wherein the hard coated film comprises substantially two layers of anintermediate layer which coats the top surface of a resin molded bodyand an outermost layer which coats the top surface of the intermediatelayer, and after the resin molded body is coated with the coatingcomposition and heat-treated in air or in humidified air, a coated filmthickness of two layersin total is between 10 μm and 200μ.
 5. Anaircraft window of synthetic resin having hard coated film according toclaim 4 wherein a coated film thickness of the intermediate layer is 1μm or more and below 50 μm.
 6. An aircraft window of synthetic resinhaving hard coated film according to claim 3 wherein the coatingcomposition contains paradium catalyst.
 7. An aircraft window ofsynthetic resin having hard coated film according to claim 4 wherein thecoating composition for the outermost layer contains paradium catalyst.8. A method for producing an aircraft window of synthetic resin havinghard coated film for an aircraft cabin window comprising the steps of:coating a coating composition containing perhydropolysilazane or itscondensation polymer which is substantially soluble in organic solventon the surface of a synthetic resin molded body, heat-treating the bodyat approximately ambient temperature to 100° C. in air or humidified airto obtain a hard coated film having siloxane bonds and/or silazanebonds, facing an outer synthetic resin molded body having the hardcoated film on the outside surface of the aircraft with an innersynthetic resin molded body so that surfaces having no hard coated filmof the two bodies are faced each other, and forming at least adouble-pane construction with a hollow interspace therebetween.
 9. Amethod for producing an aircraft window of synthetic resin having hardcoated film for an aircraft cockpit, canopy, or windshield windowcomprising the steps of: coating a coating composition containingperhydropolysilazane or its condensation polymer which is substantiallysoluble in organic solvent on the surface of a mono-layer or multi-layersynthetic resin molded body, heat-treating the body at approximatelyambient temperature to 100° C. in air or humidified air to obtain a hardcoated film having siloxane bonds and/or silazane bonds, disposing thecoated mono-layer or multi-layer synthetic resin molded body so that thecoated surface is faced outside of the aircraft, and forming a singlepane construction including a mono-layer or multi-layer pane.
 10. Amethod for producing an aircraft window of synthetic resin having hardcoated film according to claim 8 or 9 wherein the film obtained bycoating the coating composition on the surface of the synthetic resinmolded body and heat-treating in air or humidified air has a thicknessof 1 μm or more and below 10 μm.
 11. A method for producing an aircraftwindow of synthetic resin having hard coated film according to claim 8or 9 wherein the hard coated film comprises substantially two layers ofan intermediate layer which coats the top surface of a resin molded bodyand an outermost layer which coats the top surface of the intermediatelayer, and after the resin molded body is coated with the coatingcomposition on the surface of the synthetic resin molded body andheat-treated in air or in humidified air, a coated film thickness of twolayers in total is between 10 μm and 200 μm.
 12. A method for producingan aircraft window of synthetic resin having hard coated film accordingto claim 11 wherein a coated film thickness of the intermediate layer isbetween 1 μm and 50 μm.
 13. A method for producing an aircraft window ofsynthetic resin having hard coated film according to claim 10 whereinthe coating composition contains paradium catalyst.
 14. A method forproducing an aircraft window of synthetic resin having hard coated filmaccording to claim 11 wherein the coating composition for the outermostlayer contains paradium catalyst.